WO2011036407A1

WO2011036407A1 - System for transferring major loads, in particular between a floating unit and a turret pivotably mounted in the floating unit and moored to the seabed

Info

Publication number: WO2011036407A1
Application number: PCT/FR2010/051987
Authority: WO
Inventors: Bernard Dupont; Stéphane PAQUET
Original assignee: Technip France
Priority date: 2009-09-24
Filing date: 2010-09-22
Publication date: 2011-03-31
Also published as: FR2950314A1

Abstract

The invention relates to a system for transferring major loads, in particular between a first unit (1) such as a floating unit with rotary mooring to a single point and a second unit (2) substantially immobile relative to the seabed and pivotably mounted in the first unit, such as a turret pivotably mounted in a well (3) passing through the shell of the floating unit, moored to the seabed, the system including an arrangement for guiding the turret including rotary elements inserted between the two units as well as a means for absorbing deformations, mainly of the first unit. The system is characterised in that the guide arrangement includes an axial abutment (9) which contains a large number of rotary elements (15), regularly distributed to form at least one crown (14) coaxial with the axis of rotation, and in that the rotary elements (15) are capable of deforming elastically in order to absorb said loads. The invention can be used for floating units with a single-point rotary mooring system.

Description

System adapted for the transfer of heavy loads, in particular between a floating unit and a turret mounted as a pivot in the floating unit and moored on the seabed.

The invention relates to a system adapted for the transfer of heavy loads, in particular between a first unit such as a single-point rotary mooring floating unit and a second unit substantially immobile relative to the seabed and pivoted in the first unit, such as a turret pivotally mounted in a well extending vertically through the hull of the floating unit, moored to the seabed and traversed by fluid transfer conduits to installations on the floating unit, the system comprising, for the transfer of charges between the second unit and the first unit, a guiding arrangement comprising rotation elements interposed between the two units as well as deformation absorbing means, in particular of the first unit, produced, where appropriate by the stresses exerted to 1 ¹ environment.

The invention particularly relates to the case of floating units with turrets of large diameter, for example 25 meters, necessary to accommodate a large number of fluid transfer lines, for example 50 pipes. Under these conditions, the guidance system of the turret rotating in the well of the floating unit must withstand high loads, namely the static and dynamic anchoring loads, the loads transmitted by the transfer lines, also static and dynamic , turret weights and on-board equipment, including rotating fluid transfer systems, which are static, as well as dynamic due to the mass of the rotating turret and its equipment, undergoing accelerations due to the movements of the unit floating. It turns out that vertical forces that must be taken up by the guidance system could be for example of the order of 10000 to 15000 tons and the radial forces for example of the order of 1000 to 1500 tons.

To solve the problem of the recovery of very large loads in systems comprising large diameter rotating turrets, it is known from US Pat. No. 6,990,917 to use a turret which comprises a top plate at least support of the abutment. axial and a lower plate for fixing the anchor lines and a number of connection columns of the two plates and whose upper plate is configured to absorb constraints. To this end, this upper plate comprises a hub and an outer annular portion connected to the hub by a plurality of radial ray elements.

The invention aims to provide the problems posed by the turret of a large diameter, a simpler solution than that given in the US patent.

To achieve this purpose, the system according to the invention is characterized in that the guide arrangement comprises an axial abutment which comprises a large number of rotation elements, which are regularly distributed in the form of at least one coaxial crown to the axis of rotation and in that the rotation elements (15) are elastically deformable elements for the absorption of said charges and deformations.

According to one characteristic of the invention, the system is characterized in that the axial abutment comprises a plurality of crowns superimposed and spaced in the direction of the axis of the well.

According to another characteristic of the invention, the system is characterized in that in each ring the rotation elements are arranged between an annular platform, integral with the turret and a platform integral with the floating unit. According to yet another feature of the invention the system is characterized in that the platforms of the turret are mounted on the cylindrical outer face thereof, coaxial with the axis of the turret.

According to yet another characteristic of the invention, the system is characterized in that at least some of the integral platforms of the floating unit (1) are mounted on an annular support structure established on the upper deck of the floating unit around of Wells.

According to yet another characteristic of the invention, the system is characterized in that some of the platforms of the floating unit are placed in an upper part on a larger diameter than that of the well.

According to yet another characteristic of the invention, the system is characterized in that the rings of the axial abutment are juxtaposed between the bridge of the floating unit and a wide platform of the turret, coaxially with the axis of the well.

According to yet another feature of the invention the system is characterized in that the surfaces of the bridge and the platform are inclined downwards towards the axis of the well or vice versa.

According to yet another characteristic of the invention the system is characterized in that it comprises a radial bearing which comprises at least one ring of elements of elastic rotation, placed in an annular space of the well, between the turret and the unit floating.

According to yet another feature of the invention the system is characterized in that the radial bearing comprises a plurality of coaxial rings superimposed spaced in the direction of the axis of the well. According to yet another characteristic of the invention, the system is characterized in that the radial bearing may comprise at least one ring of rigid cylindrical rollers interposed between the turret and a surface of the floating unit.

According to yet another characteristic of the invention the system is characterized in that the rotation elements consist of wheels which are grouped in pairs whose axles are axially aligned and therefore common and in that the aligned axles are oriented radially by relative to the axis of the well.

According to yet another characteristic of the invention, the system is characterized in that the wheels of the axial abutment are carrying axles, that the common axle is carried by a support fixed on the platform of the turret or the floating unit. and in that the wheels are in rolling contact with the lower surface of the adjacent upper platform of the floating unit or turret.

According to yet another feature of the invention the system is characterized in that the radial bearing wheels are axle bearing and are grouped in pairs having a common axle.

According to yet another feature of the invention the system is characterized in that the common axle is carried by a support which is fixed on the cylindrical outer face of the turret or the floating unit and that the wheels are in position. bearing contact with the surface facing the surface provided with the supports of the pairs of wheels.

According to yet another characteristic of the invention, the system is characterized in that the rotation elements are non-load bearing wheels or rollers which are in rolling contact with a surface of the turret and a surface of the floating unit. According to yet another characteristic of the invention, the system is characterized in that a plurality of wheels or rollers are grouped so as to form a vehicle which moves on a circular path coaxial with the axis of the well around it and in this respect that each crown is formed by a succession of vehicles coaxial with the axis of the well.

According to yet another characteristic of the invention the system is characterized in that the rollers of the axial stop are cylindrical or conical rollers.

According to yet another characteristic of the invention the system is characterized in that the conical roller axles are inclined downwards towards the axis of the well or vice versa.

According to yet another characteristic of the invention, the system is characterized in that the rollers of the radial bearing are cylindrical or conical rollers.

According to yet another characteristic of the invention, the system is characterized in that the wheels are tires or wheels with elastically deformable solid tires.

According to yet another characteristic of the invention, the system is characterized in that the rollers are made of an elastically deformable material or elastic bandage or consist of a pressurized envelope.

According to yet another characteristic of the invention, the system is characterized in that the rotation elements are elastic balls interposed between the bearing contact surfaces of the turret and the floating unit and which are arranged in rotation cages. .

According to yet another characteristic of the invention the system is characterized in that the balls are arranged in a ring for the transfer axial loads for use in an axial abutment.

According to yet another feature of the invention the system is characterized in that the balls are arranged in a ring for the transfer of radial loads for use in a radial bearing.

According to yet another feature of the invention the system is characterized in that the balls are arranged in a ring for axial and radial load transfer, which is used simultaneously as axial stop and radial bearing, the balls being in angular contact. .

According to yet another feature of the invention the system is characterized in that a ring is provided with an outer raceway connected to the outer face of the turret to ensure that in case of a deflection of the turret of its central position in the well, not only the rotation elements on the side of the deviation, but also located diametrically opposite participating in the absorption of stresses.

The invention will be better understood, and other objects, features, details and advantages thereof will appear more clearly in the explanatory description which follows, with reference to the accompanying schematic drawings, given solely by way of example, illustrating several embodiments of the invention and in which:

FIG. 1 is a diagrammatic view of a floating unit provided with a turret mounted pivotally in a vertical well-shaped opening through the body of the floating unit, the turret being moored to the seabed by lines anchoring and traversing by transfer lines of a fluid such as oil;

FIG. 2A is a sectional view in a vertical plane, perpendicular to the longitudinal direction of the floating unit and shown, in elevation, a first embodiment of a turret guidance system in the well of the floating unit;

FIGS. 2B and 2D are top views of elastic wheel rings respectively of an axial stop and of a radial bearing of the system according to FIG. 2A;

FIGS. 2Ca to 2Cc are three views showing a pair of elastic wheels in views respectively along the indicated direction IICa-IICa of FIG. 2B, perpendicular to this direction and from above;

FIG. 3A is a view similar to FIG. 2A and shows a first embodiment version of the mode represented in FIG. 2A;

Figure 3B is a view corresponding to Figure 2Ca, however with a rolling element consisting of two twin wheels;

FIG. 4A is a view similar to view 2A, of another embodiment of this embodiment;

- Figure 4B is a top view of a portion of the radial bearing of Figure 4A;

FIGS. 5A to 5D are schematic views explaining the effect produced by the radial bearing of FIGS. 4A and 4B;

FIG. 6 is a view similar to FIG. 2A of another embodiment of the system according to FIG. 2A;

- Figures 7A to 9 are views similar to Figure 2A, three different versions of a second embodiment of the system according to the invention, Figure 7B is a top view of the ring of Figure 7A;

FIG. 10A is a view from above of a ring of elastic wheels according to a third embodiment, the ring being formed by a succession of vehicles with four elastic wheels, arranged around the axis of the well;

- Figures 10B to 10D are three different views of a vehicle according to Figure 10, respectively in section along the line Xb-Xb, perpendicular to this direction and from above;

FIG. 11A is a view similar to FIG. 2A, showing a fourth embodiment of the invention;

- Figure 11B is a top view of the ring of the axial abutment of Figure 11A;

FIG. 11C is a sectional view along the line XIc-XIc of FIG. 11B, but on a larger scale;

Figure 11D is a top view, on a larger scale, of a two-roller vehicle of Figure 11B;

FIG. 11E is a view from above of the radial bearing of FIG. 11A;

Fig. 11F is a partial sectional view, on a larger scale, along line XI-XIf of Fig. 11E;

- Figure 11G is a view, on a larger scale, with tear, in the direction of the arrow Xlg of Figure 11E;

FIG. 12A is a view from above of a part of the crown of a radial bearing of a fifth embodiment of the invention, in which the rotation elements are formed by elastic balls;

Figure 12B is a sectional view along the line XIIIb-XIIb of Figure 10B, on a larger scale;

FIG. 12C is a view, broken away, and on a larger scale in the direction of the arrow XIIc of FIG. 12A;

Fig. 12D is a view in the direction of arrow X11d of Fig. 12C; - Figure 13A is a top view of a portion of a ring of an axial stop whose rotation elements are formed by elastic beads;

- Figure 13B is a sectional view, on a larger scale, along line XIIIb-XIIIb of Figure 13A;

FIG. 13C is a view, broken away and on a larger scale, in the direction of the arrow XIIIc of FIG. 13A;

Fig. 13D is a top view of a portion of Fig. 13A;

- Figure 14A is a top view of another embodiment of a resilient ball ring according to the invention, which can serve as an axial stop and radial bearing;

Figure 14B is a sectional view, on a larger scale, along the line XIVb-XIVb of Figure 14A;

- Figures 15 and 16 are views similar to Figure 2A of an elastic ball system respectively comprising an axial stop and a radial bearing and a ring of balls forming both the axial stop and the radial bearing;

- Figure 17A is a view similar to Figure 2A but the axial stop is provided with damping devices;

- Figure 17B is a top view of the axial stop of Figure 17A, equipped with the damping device;

FIG. 17C is a plan view of the radial bearing of FIG. 17A, which is provided with damping devices;

Figures 17D and 17E are views of a damping device according to the invention respectively in elevation and from above;

FIGS. 18A and 18B schematically illustrate two possibilities of implementing a pair of elastic wheels according to the invention that can be used in the context of the first embodiment of the invention (Figure 2A);

- Figure 19 is a view similar to Figure 7A, but shows a plate and a facing face, which have inclined housing surfaces of the ring.

FIGS. 20A and 20B illustrate the possibility of producing cylindrical and conical rollers by assembling individual wheels.

The invention will be described hereinafter in its application to an installation as shown in FIG. 1. This installation comprises a floating unit 1 for producing, storing and discharging a fluid, particularly a petroleum fluid, and a turret 2 which is pivotally mounted in a well-shaped opening 3 extending entirely vertically through the body of the floating unit. The turret is moored to the sea floor by anchor lines 4 which are fixed at 5 to the base plate 6 of the turret. The figure shows two of a large number of fluid transfer lines 7, for example oil, one end of which goes to unrepresented well heads, while the upper portion of the lines passes through the turret to transport the fluids to different equipment of the floating unit.

The turret 2 is guided in the well 3 by guide arrangements which comprise an axial abutment device and a radial bearing, which will be described below and which are able to absorb the large loads produced by the turret and the displacements of supports resulting from the deformations that the floating unit undergoes under the effect of wind and waves.

The guide arrangements are adapted for the transfer of heavy loads between the turret and the floating unit. The turret may have a large diameter for example greater than 25m and the floating unit may have a length greater than 300m. These indications have not been data taken from example to give an idea of the dimensions. It is for the same purpose that some figures show people for reference.

Figures 2A to 2D illustrate a first embodiment of the invention. The axial guide arrangement 9 which constitutes an axial abutment comprises a plurality of annular platforms 12, 13 in particular horizontally and coaxial with the axis of the turret and the well and superimposed in the direction of these axes. The platforms 12 are secured to the turret 2 which at least in the example shown above the bridge 10 of the floating unit. The platforms 13 are mounted on a support structure in the form of an annular tower 19 mounted on the bridge 10 coaxial with the axis of the well 3. The annular platforms 12 and 13 are arranged so that each platform 12 is associated a platform 13 so as to form a pair. Between each pair of platforms 12 and 13 is interposed a ring 14 of rotating elements in the form of 15 elastically deformable wheels.

The trays 12 of the turret are mounted on the outer cylindrical surface thereof and are spaced apart by a distance allowing the engagement between two platforms 12 of a platform 13 of the floating unit and the arrangement between the lower face of the the platform 12 below this platform 13 and the latter of a ring 14 of rotating elements.

FIG. 2B shows the circular arrangement in the form of a ring 14 of the rotary elements 15 of the axial stop. As seen in FIGS. 2B and 2Ca and 2Cb, the cylindrical wheel shaped rotating members 15 are arranged in pairs, the wheels of each pair being mounted on a support post 21 which extends vertically upwards from the upper face of the bridge 10 of the floating unit or the upper face 22 of the annular platforms 13. The two wheels are rotatably mounted on the support pole 21 by a horizontal axle 23, the two axles 23 of the wheels being aligned and oriented radially to the axis of the well. The two wheels are in rolling contact with the lower face of the plate 12 located above the plate 13, this surface therefore constituting a raceway. It should be noted that the wheels could be of various natures, provided they can deform elastically in the directions of absorption of the charges. The wheels could be, for example, tires or wheels with a solid elastically deformable tire.

It should be noted that the platform 12 is continuous and annular because it constitutes the track; the platform 13 is not necessarily continuous because it supports discontinuous elements.

The radial bearing 24 interposed between the inner face

20 of the well 3 and the outer face 26 of the turret 2 has a plurality of rings 25, for example four pairs of wheels 15, which are superimposed in the axis of the well and the turret, being spaced between the bridge upper 10 of the floating unit to a level a little below the half-height of the floating unit. The pairs of wheels are arranged in the manner shown in Figures 2Ca to 2Cb, the support posts 21 being secured to the inner face 4 of the well.

Thanks to the configurations of the axial abutment and radial bearing, which have just been described, the invention allows the presence of a large number of elastically deformable wheels 15 whose diameter corresponds to the height of man, as indicated schematically. For example, each axial stop may comprise forty pairs of wheels, that is to say 80 wheels. Since the abutment comprises 6 crowns, the axial abutment thus comprises, in total, 480 wheels. Regarding the radial bearing, in the example shown, it comprises, in each ring, 40 pairs of wheels, that is to say 80 wheels. In total, the radial bearing therefore comprises 320 wheels.

Figure 3A shows another implementation version of the axial abutment and the radial bearing, the concept of Figure 2A. In the case of Figure 3A, the well 3 is stepped and has an upper portion 27 of larger diameter, extending, in the example shown, approximately one third of the height of the floating unit and a lower well portion 28 of smaller diameter. The diameter of the upper well portion 27 is chosen such that the annular space formed between the inner cylindrical wall of the well portion 27 and the outer cylindrical surface of the turret 2 allows the reception of two axial abutment crowns 14 such as as shown in Figure 2 and described with reference to it.

In the implementation version of the radial bearing of FIG. 3, only two rings 25 are required, each pair of wheels however having twin wheels 15 ', shown in more detail in FIG. 3B.

Twin wheels could also be used, if necessary, in the axial stop. In this case, however, the wheels are independent, that is to say they can rotate independently relative to each other around the same geometric axis.

FIGS. 4A and 4B show an embodiment which comprises an axial stop 9 corresponding to that of FIG. 2. On the other hand, the radial bearing 24 has a feature which ensures a better use of the rotation elements 15. To obtain this effect, one provided for each ring 25 of the radial bearing an outer race 30 which is connected to the outer face of the turret 26 by crosspieces 31.

The schematic figures 5A to 5D illustrate the advantageous effect produced by the outer track 30 by comparing a single-track radial bearing according to Figures 5A and 5B. Figures 5C and 5D illustrate the operation of the dual track radial bearing.

FIG. 5A shows a radial single track bearing according to FIGS. 2 and 3, in the state without radial load and therefore without radial deviation of the turret. In Figure 5B, the turret 2 has moved slightly to the right, which results in a deformation of the wheels 15 by the cylindrical outer surface 26 of the turret. The wheels on the left are no longer in contact with this inner surface and therefore do not participate in the absorption of the radial loads produced by radial deflection of the turret.

FIGS. 5C and 5D show that the presence of the outer race 30 which is integral with the outer cylindrical surface 26 of the turret, results in a radial deviation to the right, in accordance with FIG. 5D, also causing a displacement towards the right of the outer race 30, so that the wheels 15 diametrically opposed to the wheels deformed by the outer surface 26 of the turret are also deformed and therefore participate in the absorption of radial loads. Thanks to the participation not only of the wheels on the deflection side but also of the radially opposed wheels, the number of wheel crowns, in the version shown in FIGS. 4A and 4B, using a dual-track radial bearing, is reduced from 4 to 2, compared with Figure 2.

FIG. 6 illustrates an embodiment which is similar to that shown in FIG. 3A, inasmuch as two rings 14 of the axial abutment are disposed in an upper zone of larger diameter of the well 3. On the other hand, differently from the 3, the turret comprises three portions, an upper portion 37 of smaller diameter and whose cylindrical outer face supports six superimposed annular platforms 12, an intermediate portion. frustoconical 38 'conically widening downwards and a lower cylindrical portion 39 which is provided with the anchor line fixing plate 4 and the arrival of the transfer lines 7 of the fluid. The radial bearing is also different from that of FIG. 3 since it comprises only two rings of non-deformable rollers 42, possibly made of metal, namely a ring at the bottom of the support structure 43 of the annular platforms 13 and another at the top of this support structure. For this purpose, the support tower comprises at the top and at the bottom an annular radial projection 44 which extends radially towards the axis of the well. It can be seen that the two rings of rollers 42 are arranged at the level of the radially reduced portion 37 of the turret 2.

FIGS. 7A and 7B show a second embodiment of the invention, the particularity of which lies in the fact that the axial stop 9 comprises five rings 14 of wheels 15 which are arranged in the radial direction of the well and the turret, between the upper deck 10 of the floating unit and a very wide single radial platform 46 at the head of the turret 2. Due to this arrangement of the axial abutment, the radial bearing 24 has only one crown 25 of twin wheels 15 'disposed near the upper deck 10 of the well. This arrangement makes it necessary to obtain a greater resistance to the rotation of the axial abutment 9. Between each concentric row there can be sufficient room for operator access and maintenance.

To have enough room for the arrangement of the radially juxtaposed crowns 14 of the axial stop, the diameter of the well 3 is reduced in a cylindrical upper portion 47 of the floating unit, the intermediate portions 48 and lower 49 being respectively frustoconical and cylindrical. The turret 2 has a complementary shape and comprises therefore a reduced cylindrical upper cylindrical portion 50, a frustoconical intermediate portion 51 and a cylindrical lower portion 52 which is provided with the lower anchoring line anchoring platform 4. It is also possible to use in the radial bearing 24 to the place of the twin wheel crown 15 ', a ring of metal rollers 45, as shown in FIG. 8.

FIG. 9 shows another version of the system according to FIG. 7A, which is distinguished from the latter by the fact that the bearing track denoted 54 of the upper bridge 10 is inclined downwards in the direction of the axis of the well. This inclined track is advantageous in particular to reduce or cancel the efforts to be taken by the radial bearing.

FIG. 19 shows yet another embodiment of the system according to the invention, which comprises a wide turret plate with juxtaposition of a plurality of rings 14 of wheels, which are in rolling contact with the lower face of the plate 46 and whose support posts 21 are mounted on a suitable surface of the floating unit, around the well 3. The rolling surface of the plate 46 which is conical and the mounting surface of the support posts are inclined downwards the axis of the well, an important angle of, for example 30 °, which allows the removal of a specific radial bearing. Thus the guidance of the turret is achieved by a single tapered bearing. The taper is chosen according to the forces applied to the turret. Of course, it would also be possible to incline downwardly when the axis is moved away.

FIGS. 10A to 10D show a third embodiment of the invention, the particularity of which lies in the implementation of the axial stop. In this embodiment, the axles of the wheels are no longer carrying axles but are in direct rolling contact with the surfaces forming the bearing tracks of the platforms 12, 13 integral with the turret 2 and the floating unit 1. As shown in Figures 10B to 10D, the wheels 15 are arranged in pairs whose axles 23 are axially aligned. Each time two pairs of adjacent wheels are connected to each other by a connection bar 56 to form a vehicle 54 with four wheels. The aligned axles of the two pairs are oriented radially with respect to the axis of the well. Each pair of wheels of a vehicle is mounted by a roller 55 in a guide rail 57 which is fixed on the lower face forming the bearing track of the upper plate of each pair of plates 12, 13 between which the wheels are arranged. The use of the principle of non-load bearing axles has the advantage of ensuring a balance achieved directly at the level of the elastic tire of the wheels, whereas, in the case of axles, the load taken up by the wheel at its tire is fully transmitted to the axle via the sidewalls of the tire. Moreover the capacity of absorption of the deformations is doubled.

The axial abutment thus consists of a vehicle train 54 with four wheels, each vehicle following a circular path coaxial with the axis of the well.

FIG. 11A illustrates a fourth embodiment of the invention, which differs from the preceding embodiments in that the rotation elements of the axial stop 9 are formed by elastic conical rollers 60, the axis of which is oriented horizontally and whose diameter decreases towards the axis of the well. These tapered bearings are arranged between bearing tracks 61 and 62 respectively inclined complementary to the upper deck 10 of the floating unit and a suitable platform 63 to the head of the turret 2. FIGS. 11C and 11D illustrate the assembly tapered rollers 60. These are arranged in pairs so that each pair constitutes a vehicle 64 which comprises a radially inner connecting bar 65 and a radially outer connecting bar 66 of the rollers, each bar being bent and oriented so that the axles of the rollers extend radially with respect to the axis of the well. The elastic rollers may be of any material or suitable arrangement, for example pneumatic rollers or elastic tread rollers. Each vehicle is connected to a guide rail 67 coaxial with the axis of the well via two devices of two rollers 68, each disposed in the axial alignment of the axle of a roller 60, so that the two rollers engage in a guide path, about the axis of the well, which is formed by the rail 67. The guide path is made so that the rollers have only one degree of freedom which is moving towards the periphery of the well.

As shown in FIGS. 11A, 11E to 11G the radial bearing 24 comprises a ring of cylindrical elastic rollers 70 which are mounted between an upper support 71 and a lower support 72, which extend coaxially with the well axis and are formed by elements 74, articulated to each other in the manner of the elements of a chain at the axles of the rollers so that a member or chain link retains two adjacent rollers.

The axle 76 of each roller 70 carries a piece 77 in the shape of an L whose one branch is secured to the end of the axle while the other leg which extends parallel to the axis of the axle 76, door at its free end one or two rollers 78 whose axis of rotation is oriented perpendicular to the axis of the roller and which are retained in a guide rail 80 in the shape of an L of which one end is fixed on the upper surface of an annular support 82 itself fixed on the surface of the well 3. It is noted that the cylindrical rollers 70 are arranged between the turret and the surface of the well, in rolling contact with the outer and inner surfaces of the turret and the well respectively, and are immobilized in the direction of the axis of the well. It should be noted that the rollers of the axial stop 9 may also be cylindrical rollers. In this case it is advantageous that the rollers consist of independent twin wheels.

FIGS. 12A to 12D illustrate a fifth embodiment of a radial bearing 24, which has the particularity that the rotation elements are formed by a row of radial contact elastic balls 82, which are retained in a rolling cage 84 between an inner ring 85 connected to the turret and an outer ring 86 connected to the well, which constitute rolling tracks respectively fixed to the turret and the face of the well. We find that the tracks are concave. The rolling cage 84 comprises four circular rails 88 arranged coaxially with the axis of the well, two rails at the inner ring 85 and two near the outer ring 86. The cage is supported by two support rollers 89 on a platform radial annular 91 secured to the turret and by a roller 89 on the outer ring 86. The four rails are interconnected by cross members 90 which carry at their center elements in the form of spherical caps 90 'which are in contact with each other. bearing with the balls.

FIGS. 13A to 13D show an elastic ball thrust bearing, which is intended to act as axial stop 9. The balls are arranged between two concave rings 92 and 93 respectively upper and lower in a cage 84 like the balls of the radial bearing. The support rollers 89 are in rolling rest on the lower ring 93 and a radial guide member 94 is also provided on the radially inner side. The lower and upper rings are then secured respectively to the bridge 10 of the floating platform 1 and the upper plate of the turret. The rings have a convex shape trapping the balls and reducing the ball / track contact pressure.

FIGS. 14A and 14B show an oblique-contact ball bearing which can serve both as an axial abutment and as a radial bearing. In this case the lower ring and the upper ring are convex and cover an angular extent of 45 ° in a vertical plane to be able to retain both axial and radial forces. The lower rings 93 and 92 are respectively integral with the bridge 10 of the floating unit 1 and the platform 63 of the turret 2, firstly, in the use of axial stop, or the well of the floating unit and the turret on the other hand in the case of use as a radial bearing. It can be seen that the cage is turned at an angle of 45 °, the angle can be different, to be chosen according to the forces applied to the turret, with respect to FIG. 10. The support rollers 89 are in rolling rest on the lower cage 93 and a piece 92 'projecting outwardly of the upper cage 92.

Figures 15 and 16 illustrate the guidance of the turret by combining an axial abutment and a radial bearing, described above (Figure 15) and a row of angular contact balls (Figure 16).

FIGS. 17A to 17D show a system according to FIGS. 2A to 2C, whose axial abutment and the radial bearing are provided with a damping device denoted 95. This device comprises a support 96 of a damping cylinder 97 whose rod mobile 98 carries at its end a roller 99 whose axis of rotation is perpendicular to the axis of the rod.

To equip the axial abutment 9 damping means is disposed in the ring pairs of wheels 15, a plurality of damping devices 95 whose support is mounted on the bridge or an annular platform of the floating unit while the roller is in bearing contact with the rolling track of the corresponding annular platform of the turret. As shown in FIG. 17B, the damping devices are arranged around the well, in the circumferential direction, in the ring here every two pairs of wheels.

Figure 17C shows the arrangement of the damping devices 95 in the radial bearing, between the turret and the well surfaces.

It can be seen that the damping devices are arranged in parallel with the rolling elements guiding the turret. The device comprises damping cylinders of any known type, for example hydraulic, viscoelastic or friction type. The damping properties can also be included in the rolling elements for example by filling the tires. It should be noted that the arrangement and the distribution of the damping devices in the axial abutment and the radial bearing have only been given by way of example and may be different depending on the damping result that it is desired to obtain. .

Figures 18A and 18B illustrate two versions of an axial stop with tapered raceways. In the case of FIG. 18A, the wheels comprise a band of cylindrical rollers. It should be noted that the taper angle of two tracks is chosen so that the extension lines of the conical surfaces and the axis of the common axle intersect at a single point on the axis of rotation.

In FIG. 18B the wheels have a conical tread, the angle of which is chosen so that the extension of the conical faces of the tread tracks as well as the axis of the axle intersect at the same point on the tread. the axis of rotation.

It should be noted that placing the track of the axial abutment in the lower part of the support structure of the turret, on the underside, is an advantage of the proposed provisions in the invention because it avoids that an obstacle or contending object may damage the tires can be on the track at the time of passage of the tire (and also naturally reduces the accumulation of grease and dust that can come soiled Track.

In addition, another advantage of the arrangements made is to place the tire support on the side of the boat. Not only, it can more easily operate in maintenance, but in addition, it is easy to wire the equipment, including 1 instrumentation monitoring the behavior of rolling elements.

Of course, various modifications can be made to the invention as described and shown in the figures. Indeed, the different versions and embodiments have been given by way of example. Thus, as shown in FIGS. 20A and 20B, the cylindrical and conical rollers can be made by assembling and axially juxtaposing several individual elastic tire wheels 100. In the context of the invention, particularly in the case of tires, it can be considered to minimize the rolling resistance coefficient of tires, as good tire adhesion performance is not sought. It might even be advantageous to minimize track / tire friction. For example the bearing track could be made of a material promoting sliding, where appropriate by lubrication. It is also possible to consider inflating tires with water to prevent deformation under load. All solutions are applicable to elastic rolling members, which could be formed by fretted elastomers, composites or the like. Many track / tread combinations are possible for the axial stop:

flat runway / cylindrical tread (Figure 2A): rolling bearing due to the difference between outer and inner circumferential speeds;

- Tapered track / cylindrical tread (Figure 18A): the tread adapts by deformation specific to the conicity of the track for a rolling without sliding and loss by elastic deformation;

tapered track / tapered tread (figure 18B): geometrically compatible tread and track with a non-slip bearing and no elastic deformation losses.

It should also be noted that the functions of the integral platforms of the turret and the floating unit are interchangeable.

On the other hand, the invention has been described in its application to a single-point mooring floating unit via the turret. Naturally, the invention can be used by any system presenting the same problem or a similar problem.

Claims

1. A system adapted for the transfer of heavy loads, in particular between a first unit (1) such as a single-point rotary mooring floating unit and a second unit (2) substantially immobile relative to the seabed pivotally mounted in the first unit, such as a turret pivoted in a well (3) extending vertically entirely through the hull of the floating unit, moored on the seabed and traversed by conduits (7) for transferring fluid to installations on the floating unit, the system comprising, for the transfer of charges between the second unit (2) and the first unit (1), a guiding arrangement comprising rotation elements interposed between the two units as well as means for absorption of the deformations in particular of the first unit, produced, where appropriate by environmental stresses, characterized in that the guide arrangement comprises a stop ax iale (9) which comprises a large number of rotation elements (15), which are regularly distributed in the form of at least one ring (14) coaxial with the axis of rotation and in that the rotation elements (15) ) are elastically deformable elements for the absorption of said charges.

2. System according to claim 1, characterized in that the axial abutment (9) comprises a plurality of rings (14) superimposed and spaced in the direction of the axis of the well.

3. System according to claim 2, characterized in that in each ring (14) the rotation elements are arranged between an annular platform (12), integral with the turret (2) and a fixed platform (13) of the unit floating (1).

4. System according to claim 3, characterized in that the platforms (12) of the turret (2) are mounted on the cylindrical outer face thereof, coaxial with the axis of the turret.

5. System according to one of claims 2 or 3, characterized in that at least some of the platforms (13) integral with the floating unit (1) are mounted on an annular support structure (19) established on the upper deck ( 10) of the floating unit (1) around the well (3).

6. System according to claim 5, characterized in that some of the platforms (13) of the floating unit (1) are placed in an upper part over a larger diameter than that of the well.

7. System according to claim 1, characterized in that the rings of the axial abutment are juxtaposed between the bridge (10) of the floating unit (1) and a wide platform (46) of the turret (2), coaxially to the axis of the well.

8. System according to claim 7, characterized in that the surfaces of the bridge and the platform are inclined downwards towards the axis of the well or vice versa.

9. System according to claim 8, characterized in that it comprises a radial bearing (24) which comprises at least one ring (25) of elastic rotation elements (15), placed in an annular space of the well (3) between the turret (2) and the floating unit (1).

10. System according to claim 9, characterized in that the radial bearing (24) comprises a plurality of rings (25) coaxial, superimposed spaced in the direction of the axis of the well (3).

11. System according to one of claims 1 to 7, characterized in that the radial bearing (24) may comprise at least one ring of rigid cylindrical rollers interposed between the turret and a surface of the floating unit.

System according to one of Claims 1 to 10, characterized in that the rotation elements (15, 15 ') are constituted by wheels which are grouped in pairs whose axles (23) are axially aligned and therefore common and in that the aligned axles are oriented radially relative to the axis of the well.

13. System according to claim 12, characterized in that the wheels (15) of the axial abutment (19) are carrying axles (23), the common axle is carried by a support (21) fixed on the platform ( 12, 13) of the turret (2) or the floating unit (1) and that the wheels (15) are in rolling contact with the lower surface of the adjacent upper platform (13, 12) of the floating unit (1) or turret (2).

14. System according to claim 13, characterized in that the wheels (15) of the radial bearing (24) are axle load bearing and are grouped in pairs having a common axle (23).

15. System according to claim 14, characterized in that the common axle (23) is carried by a support (21) which is fixed on the cylindrical outer face (26) of the turret (2) or the floating unit. (1) and in that the wheels (15 ') are in bearing contact with the surface facing the surface provided with the supports of the pairs of wheels.

16. System according to one of claims 1 to 12, characterized in that the rotation elements (15 ') are non-load bearing wheels or rollers which are in rolling contact with a surface of the turret and a surface of the floating unit.

17. System according to claim 16, characterized in that several wheels (15, 15 ') or rollers (60) are grouped so as to form a vehicle (34, 64) which moves on a circular path coaxial with the axis. of the well around it and in that each ring (24) is formed by a succession of vehicles coaxial with the axis of the well.

18. System according to claim 17, characterized in that the rollers (60) of the axial abutment (9) are cylindrical or conical rollers.

19. System according to claim 18, characterized in that the axles (23) of conical rollers (60) are inclined downwards towards the axis of the well or vice versa.

20. System according to claim 19, characterized in that the rollers (70) of the radial bearing (24) are cylindrical or conical rollers.

21. System according to one of claims 1 to 17, characterized in that the wheels (15) are tires or wheels with elastically deformable solid tire.

22. System according to one of claims 16 to 20, characterized in that the rollers (60, 70) are of an elastically deformable material or elastic bandage or consist of a pressurized envelope.

23. System according to one of claims 1 to 13, characterized in that the rotation elements are elastic balls (82) interposed between the bearing contact surfaces of the turret (3) and the floating unit (1). ) and which are arranged in rotation cages (84).

24. System according to claim 23, characterized in that the balls (82) are arranged in a ring for the transfer of axial loads for use in an axial stop.

25. System according to claim 23, characterized in that the balls (82) are arranged in a ring for the transfer of radial loads for use in a radial bearing (24).

26. System according to claim 23, characterized in that the balls (82) are arranged in a ring for the transfer of the axial and radial loads, which is used simultaneously as axial stop (9) and radial bearing (24), the balls being in oblique contact.

27. System according to one of claims 9 to 26, characterized in that a ring (25) is provided with an outer race (30) connected to the outer face (26) of the turret (2) for ensure that in case of a deviation of the turret from its central position in the well, not only the rotation elements on the side of the deviation, but also located diametrically opposite participating in the absorption of stresses.